Centrifugal switch



- y 1950 E. w. RICKMEYER I 2,509,527

CENTRIFUGAL SWITCH Filed Nov. 16, 1.945 2 Sheets-Sheet l y 1950 E. w. RICKMEYER 2,509,527

CENTRIFUGAL SWITCH Filed Nov. 16, 1945 2 Sheets-Sheet 2 rmaa a, so, 1050 oanrmruoar. swrrcn Ernst Walter Rickmeyer, Berkeley, in, assignor to Jeflerson Electric Company, Be

a corporation of Illinois Application November 16, 1945, Serial No. 629,057

18 Claims. (01. 200-80) The present invention relates to mercury switches of the centrifugal type. More particularly, it is concerned with the time delay element for a mercury switch of this type.

A ,mercury switch that embodies the present invention comprises a switch envelope or shell that is divided into two chambers by a partition, through which partition the mercury is adapted to pass under certain conditions and at a predetermined rate of fiow. In one chamber are disposed a pair of spaced electrical contacts that are normally insulated from each other. The gap between the contacts is bridged by a body of mercury that is disposed in this first chamber,

- and when this gap is thus bridged the electrical circuit through the switch is completed. when the mercury is caused to pass through the partition into the second chamber so as to lower the level of the mercury in the first chamber, the bridge between the spaced contacts is broken, thereby breaking the electrical circuit through the switch.

This dividing partition is adapted to support the mercury in the first chamber and allows the mercury to pass into the second chamber only when sumcient pressure is applied by the mercury against the partition to force the mercury to flow through restricted openings in the dividing partition. This force is created by spinning the switch shell about an axis that will throw the mercury against the dividing partition or by accelerating the shell in a direction that will accomplish the same result.

The present invention contemplates the use of a partition that comprises sintered particles of metal, such as steel or nickel, that are spaced apart to provide a multitude of voids therebetween. These voids serve as the restricted passages through which the mercury may flow. By varying the particle sizes and the pressure used when sintering these particles together, it is possible to vary the degree of restriction in these passages, and hence to produce time delay elea means and method for varying the time delay characteristics in accordance with specific requirements.

llwood, Ill.,

The-foregoing constitute some of the principal objects and advantages of the present invention, others of which will be made apparent upon a reading of the following description and from the drawings, in which:

Fig. 1 is a plan view of a rotating or spinning device in which is mounted a circuit controlling switch embodying the present invention;

Fig. 2 is an enlarged vertical sectional view through a mercury switch embodying one form of the present invention;

Fig. 3 is a top plan view of the switch shown in Fig.

Fig. 4 is a transverse sectional view taken on the line H 01' Fig. 2;

Fig. 5 is a fragmentary vertical sectional view corresponding to Fig. 2 but showing a diflerent form of the invention;

Fig. 6 is a view corresponding to Fig. 5 but showing still a different embodiment of the invention;

Fig. 7 is a view corresponding to Figs. 5 and 6 but showing another form of the present invention;

Fig. 8 is a transverse sectional view through a mercury switch, the view being taken on the line 8-4 ofFig. 7;

Fig. 9 is a view corresponding to Fig. '7 but showing still another form of the invention; and

Fig. 10 is a transverse sectional view through a mercury switch, the view being taken on the line lli0 of Fig. 9.

For purposes of illustration, specific embodiments of the invention have been selected, but it is recognized that modifications will occur to the man skilled in the art, and it is intended that the embodiments shown may be modified without departing from the intended scope of the invention. 7

'- Referring to the drawings and particularly to Fig. 2, the invention is shown as embodied in a mercury switch comprising a switch envelope or shell I! that contains therein a cup-like time delay element It, which divides the shell l5 into two chambers indicated at i! and iii. The shell I! has an oiifset portion providing an annular shoulder l9 upon which the cup I6 is Supp rted.

The cup i5 is open at its upper end, through which opening projects a contact element generally indicated at 20. A copper flanged element serted between the flanged member 2| and the contact member 23. A second sealing washer 24 upper end of the shell I! is crimped over, as at 26, against the washer 24. The contact member 20 is thus-sealed in place in the upper end of the shell I.

This contact member 23, as shown, comprises a body portion 26 of Bakelite, or like material, that is molded about a cup-like conducting member 21 that projects through the body' portion 26 and provides an exposed surface at 28 at the lower end of the contact member 20. This cup-like member 21 may be made of copper or like electrical conducting material.

Mercury normally fills the chamber ll of the cup it, as shown at 23. This mercury serves as an electrical conductor between the exposed portion 23 of the conducting member 21 and the wall of the cup It. This cup l3 likewise is made of an electrical conducting material, and engages the wall of the shell l5, which likewise is made of a good electrical conducting material. A copper ring 30 surrounds the shell l and makes good electrical contact therewith. Thus, the circuit through the mercury can be traced from the conducting member 21, which constitutes one lead terminal, through the mercury 28, cup l6, shell I5, and finally through the ring 30, which constitutes the other lead terminal to the mercury switch.

The cup l6 constitutes the time delay element through which the mercury 29 passes in flowing into chamber Hi. This cup is made of sintered particles of metal, such as steel or nickel, between which particles are provided the voids that constitute restricted passages. As shown, the entire cup I6 is made of these sintered metal particles, though it is recognized,- of course, that the lower portion, or bottom only, of the cup may be so made.

As shown in Fig. l, the mercury switch indicated at 14 may be mounted on a disk 3i that is adapted to rotate about a shaft 32. The mercury switch It is mounted so that the upper end of the shell l5, shown in Fig. 2, is disposed closest to the shaft or axis of rotation 32. Thus, as the disk 3| is rotated in the direction of the arrow, the centrifugal force causes the mercury 29 to be urged against the bottom of the time delay cup l6.

When the mercury switch is at rest and during normal conditions of handling, the bottom of the cup I6 is adapted to support the mercury in chamber l'l without their being any leakage of the mercury into chamber i8. It is only upon the reaching of a predetermined centrifugal force resulting from the rotation of the disk 3| that the mercury 29 is caused to apply sufficient pressure against the bottom wall of cup l6 that this mercury is forced through the passages or voids between the sintered metal particles into the chamber I8. Because of the nature of the restricted passages between the particles and further due to the fact that the mercury entering the second chamber must displace the air or gas that is initially disposed in this second chamber, a certain time is required for the mercury 29 to flow into the second chamber. As soon as the level of the mercury is disposed below or out of contact with the exposed portion 28 of the contact member 20, the circuit through the switch It is broken.

As shown, the centrifugal force required to cause the mercury to flow through the passages 4 T in the time delay cup I! is created by the rotation of the disk 3|. It is recognized, of course.

that suflicient force may be provided in other ways. such, for example. by accelerating the mercury switch in a direction and to a sufllcient d egree to effect this same result.

. As previously mentioned, the time required for the mercury 23 to flow through the restricted passages or voids between the sintered metal particles in cup I! is dependent upon the degree of restriction and the length of the path through which both themercury and the displaced air from chamber ll must flow. The displacement of this air or gas from chamber I8 is in a direction counter to the flow of the mercury since this gas must flow from chamber l8 into chamber H. In Fig. 6, a cup 34 is provided with its bottom wall having throughout its width a uniform thickness, and hence sintered particles that have undergone uniform pressure during the sintering process. Thus, in this form of the invention, the flow of mercury and gas through the bottom wall of the cup is more or less uniform throughout the entire area of the bottom.

In Fig. 2, on the other hand, the bottom wall is provided with a projecting portion 33 disposed substantially in the center portion of the wall. In forming this cup, the particles of metal that are disposed in this bulging portion 33 have undergone much less pressure during the sintering process than those particles disposed in those portions of the bottom wall removed from this central portion. In other words, the voids between the particles are much larger in the central portion of the bottom of cup l6 than are the voids in the remainder of the bottom wall. Thus, the flow of mercury and gas through the bottom of cup I6 is much faster than in the case of the cup shown in Fig. 6.

Thus, there is illustrated in Figs. 2 and 6 time delay cups l6 and 34 having two different characteristics. In the case of the form shown in Fig. 2, the time delay is relatively short, so that this type of cup would be used in a so-called fast acting switch. In Fig. 6, on the other hand, the time delay is considerably longer because of the much higher pressure utilized during the sintering process over the entire area of the cup bottom, and therefore the type of cup shown in Fig. 6 would be utilized in a slower operating switch.

In Fig. 5, the inner wall of the cup element 35 is curved atthe bottom thereof so as to provide a bottom wall portion having a uniform thickness where this portion is of considerably less diameter than that shown in Fig. 6. In this form of the invention, the air transfer between chambers l8 and I! would be reduced over that shown in Fig. 6 because of the longer path that would be required through the bottom wall in the regions of greater thickness. Thus, Fig. 5 represents a mercury switch having longer time delay characteristics than that shown in Fig. 6.

Figs. 7 and 8 illustrate two time delay cups having still different characteristics. In Fig. 7, the inner wall of the cup 36 is substantially hemispherical, as shown at 31, so as to provide a bottom wall having a non-uniform thickness throughout its area. Thus, in this form of the invention, if the center portion only of the wall is of a thickness corresponding to that of the a bottom wall of cup 34 (Fig. 6) then it can be time delay cup 35 is greater than in the case of cup 34. Thus, Fig. 7 illustrates a mercury switch having still a greater time delay in its operation than in the case of any of the previously illustrated embodiments of the invention.

Fig. 9 illustrates a cup 38 whose inner walls, at least in the lower region of the cup, slope inwardly substantially parabolically to provide still different time delay characteristics. In this form of the invention, there is provided a relatively small .bottom wall that is effective in allowing gas to transfer from chamber l8 to chamber II. This embodiment of the invention illustrates a very slow operating switch.

It is thus seen from the foregoing that many variations in time delay characteristics can be provided by changing the shape and form of the bottom walls of the time delay cups. There obviously are other shapes and combinations of shapes which can be used to eifect still different time delay characteristics.

1 claim:

1. A mercury switch comprising a shell, a cup in the shell with the cup bottom spaced from both ends of the shell to provide two chambers, the cup bottom comprising sintered metal particles providing voids therebetween forming continuous passages through the cup bottom, the length of the passages in certain portions 'of the cup bottom being on an average greater than those in other portions of the cup bottom, and a body of mercury in one chamber adapted to flow through the passages into the other chamber.

2. A mercury switch comprising a shell, a cup in the shell with the cup bottom spaced from both ends of the shell to provide two chambers, the cup bottom comprising sintered metal particles providing voids therebetween forming continuous passages through the cup bottom, and a body of mercury in one chamber adapted to flow through the passages into the other chamber, the relative sizes and lengths of the passages being such as to allow freer flow of mercury through the center portion of the cup bottom than through other portions.

3. A mercury switch comprising a shelL-a cup in the shell with the cup bottom spaced from both ends of the shell to provide two chambers, the cup bottom comprising sintered metal particles providing voids therebetween forming continuous passages through the cup bottom, and a body of mercury in one chamber adapted to flow through the passages into the other chamber, the relative sizes and lengths of the passages being such as to allow freer flow of mercury through certain portions of the cup bottom than through other portions.

4. A mercury switch comprising a shell, a cup in the shell with the cup bottom spaced from both ends 01 the shell to provide two chambers, the cup bottom wall comprising sintered metal particles, the space between the particles in one region of the bottom being larger than in other regions of the cup bottom, and a quantity of mercury 1n the shell adapted to pass through the said wall.

5. A mercury switch comprising a shell, 9. cup in the shell with the cup bottom spaced from both ends of the shell to provide two chambers, the cup bottom wall comprising compressed sintered metal particles, the spaces between the particles in the central region of the cup bottom being larger than in other regions of the cup bottom, and a quantity of mercury in the shell adapted to pass through the said wall.

6. A mercury switch comprising a shell, a cup in the shell with the cup bottom spaced from both ends of the shell to provide two chambers, the cup bottom wall comprising sintered metal particles, the one face of the cup bottom being bulged in the center portion thereof, and a quantity of mercury in the shell adapted to pass through the said wall.

7. A mercury switch comprising a shell, a cup in the shell with the cup bottom spaced from both ends of the shell to provide two chambers, the cup bottom wall comprising sintered metal particles, the inner side faces of said cup merging toward each other at the bottom of the cup, the outside faces of the cup being substantially flush throughout the height of the cup, and a quantity of mercury in the shell adapted to pass through the said wall.

8. A mercury switch comprising a shell, a cup in the shell with the cup bottom spaced from both ends of the shell to provide two chambers, the cup bottom wall comprising sintered metal particles, the inner surface of the cup bottom being curved while the outside bottom surface is substantially planar, and a quantity of mercury in the shell adapted to pass through the said wall.

9. A mercury switch comprising a shell, a wall in the shell spaced from both ends of the shell to provide two chambers, said wall comprising sintered metal particles, the space between the particles in one region being larger than in other regions of the wall, and a quantity of mercury in the shell adapted to pass through the said wall.

10. A mercury switch comprising a shell, a wall in the shell spaced from both ends of the shell to provide two chambers, the wall being porous, the pores in one region of the wall being larger than in other regions of the wall, and a quantity of mercury in the shell adapted to pass through the said wall.

11. A mercury switch comprising a shell, a wall in the shell spaced from both ends of the shell to provide two chambers, the wall comprising sintered metal particles, the spaces between the particles in the central region of the wall being larger than in other regions of the wall, and a quantity of mercury in the shell adapted to pass through the said wall.

12. A mercury switch comprising a shell, a wall in the shell spaced from both ends of the shell to provide two chambers, said wall comprising sintered metal particles, one face of the wall being bulged in the center portion thereof, and a quantity of mercury in the shell adapted to pass through the said wall.

13. A mercury switch comprising a shell, a wall in the shell spaced from both-ends of the shell to provide two chambers, the wall comprising sintered metal particles, one surface of the wall being curved while the other surface is substantially planar, and a quantity of mercury in the shell adapted to pass through the said wall.

ERNST WALTER RICKMEYER.

No references cited. 

